Here's How Microsoft Office Will Work On The iPad
You can download the apps from the App Store for free, and you'll be able to read documents using the apps for free. It only works on iPads running iOS 7.0 or later.
But if you want to create and edit documents, you're going to need an Office 365 subscription, which costs around $100 per year.
We got a chance to demo the new suite at the event. The apps run smoothly, as you would expect, and really integrates the use of touch in a cool way. It's especially useful for people who already use Office, as the documents and formatting options are nearly identical to the desktop version of the suite.
The goal of the Office suite, it seems, is not to offer a particularly deep set of editing and reading options, but to give users a broad set of tools for editing, tweaking and creating documents on the go.